1. Field of the Invention
The present invention relates to an apparatus, a method and a computer program product for determining a respiratory condition that determines a subject's respiratory condition.
2. Description of the Related Art
In recent years, drivers' falling asleep while driving a moving vehicle, such as a rail, a car or the like, has resulted in road accidents. A sleep apnea syndrome has recently received attention as one of the causes of the road accidents. Further, people may experience hypoxic condition, but not apnea, which may result from improper pillow height.
In addition, a chair-type child seat or a stroller causes hypoxia to children. Further, there is an increasing incidence of chronic obstructive pulmonary disease (COPD), in which an asthma attack is likely to occur during sleep, which affects, for example, 16 million people in America. Therefore, measurement of a respiratory condition during sleep has received attention.
In order to measure a respiratory condition during sleep, the degree of restrictions needs to be low. Therefore, a method for measuring heart and respiratory rates by providing a sensor in a pillow or a mattress has been researched and developed. A method for measuring respiratory-related sounds such as snoring by an external microphone has also been devised. Further, a method for measuring a pulmonary sound and a sound called rales, which is generated during asthma, by a sound sensor provided on a body has been examined (JP-A 2004-357758 (KOKAI)).
As described above, the heart rate respiratory sensor embedded in a bed measures low-frequency vibration (up to 1 Hz) according to movements of the chest based on a breathing. Therefore, it is difficult to make measurement when airway occlusion, bruxism, or the like occurs, which has a high frequency range, even though complete apnea does not occur. In addition, it is not possible for the external microphone to make measurement, when snoring, bruxism or the like does not appear to the outside as sounds. Therefore, it is difficult to detect a change in breath sounds due to the state of respiratory obstruction.